>>>>> "Doug" == Doug Stewart writes:
Doug> solve([a1*s*h1=(h2-h1)/r1 + U, a2*s*h2= (h1-h2)/r1 - h2/r2],[h1,h2]);
Notice the upper case U.
Doug> y2:ev(h22,u=1/s);
Notice the lower case u.
Maxima is case-sensitive now, so those are different.
When I change u=1/s to U=1/s (or you can change the solve part), I get
a plot that looks sensible.
The fact that there's not plot when you have u and U is a bug in plot,
but I'm not sure how to fix it. The adaptive plotter sees that the
result is not a number and thinks it's a singularity and tries to
refine the plot. But the result is never a number, so it keeps trying
for a long time until it gives up.
Ray